Process of treating artificial threads



Patented Oct. 17, 1933 UNITED STATES PATENT raocnss oF TREATING ARTIFICIAL THREADS .w

Harold H enry Parker,.Kemnore, N. Y., assignor i q to Du Pont Rayon Company, New York, N. Y.,

' a corporation of Delaware No Drawing.

Application January 10, 1930 Serial N0. 420,019

' 6 Claims, (01. 18-54) This invention relates to aprocess of treating artificial threads and more particularly to a process of desulphuring threads produced by th viscose process. r

In the manufacture of artificial threads by the viscose process; certain sulphur bodies are formed in the coagulation and regeneration steps These liquors and the sulphur. In other processes,

after thefreshly spun threads collected on a bobbin-or in a bucket are washed to remove the acid and other coagulating bath liquors, theyare either processed in the form of cakes or'bobbins 'or converted,after drying, into skeins for further treatment, includingbleaching and desu1phuring.-

To eliminate the objections inherent in the handling of the freshly spun threads, it is desirable. to perform the operations on the threads wound on bobbins, in buckets, or on cakes provided with insertsx It isobvious that the carriers on which the silk issubjected tothe treatment must be made of a material resistant to the desulphuring agents employed as well as the bath liquors. Up to the present time the most satisfactory material used for this purpose is aluminum.

The sulphides,'particularly the alkali sulphides including sodium sulphide, are the most efiicient for removing the sulphur impurities. Their use has, nevertheless, up to this time been seriously limited by the corrosion of the aluminum carriers or other parts of, the equipment, which tends to contaminate the threads and results in an inferior product. Thus, prior to this invention, it

has been necessary to resort to desulphuring processes which do not utilize the alkali sulphides and are inferior to the alkali sulphide desulphuring operation in economy as well as resulting in resulting therefrom-by adding to said solution compound, such as sodium silicate.

It'is' therefore anobject of this invention to i provide a method of desulphuring viscose artificial threads on aluminum carriers with a-sa lt i of a weak acid having an alkaline reaction and in which method the aluminum carriersare' not substantially corroded. a i v Another object of this invention is todesulphur artificial yarn produced from viscose'and disposed on aluminum carrierswith a desulphuring composition comprising an alkali sulphide, such as sodium sulphide, and an agent which subs'tantially inhibits the corrosion of the aluminum by 7 the said alkali sulphide.

Another object of-this'invention is to' provide a method ofjdesulphuring artificial ya'rn pro duced'from viscose and disposed on aluminum carriers gwhich comprises subjecting said yar'n and carriers to a desulphuringsolution com'pris- 3 ing sodium sulphide and sodium silicate."

Other objects will appear from the following "description and appended claims. V M Accordingto one manner of practicing this invention, freshly spun cakes of artificial threads 80 produced from viscose are removed from the spinning bucket and provided with resilient foraminous aluminum inserts and thenplaced on washing racks; Water oranother solution adapted to remove the coagulating bath liquor 85 from the cakes is allowed to drip onto the, cakes comprises a salt of a weak acid having an alkaline reaction such as alkali sulphide and which normally corrodes aluminum, and a compound,- such as sodium silicate, which inhibitsthe corrosion of the aluminum by said salts. Various proportions of the ingredients may beemployed. Satisfactory results have been obtained with a solution of sodium sulphide containing approximately 0.2%, of sodium sulphide and suflicient 40 B. water glass to produce 0.1% of silica (SiOz) in the final solution.

In employing this solution,it is heated to ap- .105 proximately 90 C. and allowed to drip onto the washed. cakes of artificial threads until the sulphur is substantially removed from the cakes. The cakes are then given a final wash with water to remove the desulphuring solution, afterwhich 110 they may be bleached, dyed, sized, or the like before drying.

Hard or soft water may be employed and the treatment may be carried out at any temperature. The best results are attained when the temperature is as near to the boiling point of the solution as practical. Good results, however, are obtained at lower temperatures. For example, I

have found that by immersing the cakes in the.

sodium-sulphide-sodium-silicate solution at 0., excellent desulphuring is'obtaine'd, particularly if the cakes have previously been dried in order to impart to the cakes of rayon on the special purpose of removing from the yarn any traces of the iron and copper resulting from the contamination with parts of the equipment.

. It is clear that while sodium silicate 40 B. water glass is referred to, any other grade of sodium silicate may be used as well, it being necessary to make only such adjustment of the alkalinity of the solution so thatthe silica will not precipitate.

l Though the invention has been described with particular reference to desulphuring of cakes, it

is applicable to the desulphuring of threads wound on bobbins, skeins, or in spinning buckets. It is equally applicable to yarn which has been dried or to threads in the gel state, that is, those threads which have not been submitted to'any drying operation. The desulphuring process may be also successfully practiced by immersing the yarn in the solution, by pressure or vacuum .de- 7 sulphuring, or by centrifugal desulphuring. I

.Since it is obvious that various changes and .modificationsmay be made in the specific details above described, this invention is not restricted thereto except as set forth in the appended claims. I claim 1. Theprocess of desulphuring threads prosodium carbonate and a silica content of 0.05%

, 2-. The process of desulphuring threads produced from viscose and disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing 0.2% of sodium sulphide and sodium silicate in an amount sufficient to produce a silica content of 0.10%. 3. The :process of desulphuring threads produced from viscose and disposed on aluminum carriers which comprises subjecting said threads and carriers to a solution containing sodium carbonate and sodium silicate in such proportions that the combined alkalinity Will'be 0.3 calculated as sodium carbonate and "the silic content 0.05%. r

4. A .process which comprises subjecting i threads produced from viscose and disposed on aluminum carriers to a desulphuring solution containing a salt of a weak acid having an alkaline reaction and which normally corrodes aluminum as the eifective desulphuring agent and a suificient quantity of-sodium silicate to inhibit the corrosion of saidcarriers by the desulphuring agent, the total'alkalinity of thedesulphuring solution being such as will prevent the precipitation of silica.

5. A process .which comprises subjecting threads produced from viscose and disposed on aluminum carriers to a desulphuring solution containing an alkali sulphide and asufficient quantity of sodium silicate to inhibit the corrosion of said carriers by said alkali sulphide,the

total alkalinity of said. solution being suchas the total alkalinity of said solution being such L as to prevent the precipitation ofsilica. I

' HAROLD HENRY PARKER. 

